M.J. Fradinho

Forages and grazing in horse nutrition

Apparent digestibilities of feedstuffs can be estimated using either total faecal collection (TFC) or digestibility markers. However, it is still debatable whether the use of markers results in a reliable prediction of digestibility. Four adult ponies were fed four iso-energetic rations for 24 days with insoluble ash (AIA) and titanium dioxide (TiO2). The mean digestibilities of the organic matter based Mean faecal recovery of markers as percentage of intake was 107.9 (SE 1.588), 118.9 (SE 1.726) using ADL and TiO2 variance in faecal TiO2 2 seemed to be a suitable alternative to the TFC method in order to estimate apparent organic matter digestibility of diets differing in haylage to concentrate ratios.

Effects of body condition and leptin on the reproductive performance of Lusitano mares on extensive systems

The aim of this study was to investigate the effects of body condition (BC), BC changes, and plasma leptin concentrations on the reproductive performance of Lusitano broodmares on extensive systems. Data from 119 mares (ranging from 4 to 22 years of age) were collected over a period of four consecutive breeding seasons. Each case was considered as one foaled mare bred in 1 year. Body condition changes at conception (ΔBCScon) showed a strong effect on fertility at the first two postpartum estrous cycles and a significant interaction with body condition score at conception (BCScon) was observed (P < 0.01). The best fertility results were obtained with positive and greater ΔBCScon. The best predictive value of fertility (91%) was achieved when the BCScon was 3.0 and ΔBCScon was 0.375. Global foaling rate for the 4-year period was 74.5%. Mean foaling interval and gestation length were, respectively, 368.0 ± 2.8 and 340.3 ± 1.0 days. Gestation length was influenced by the month of foaling (P < 0.05) and decreased as mares got older (P < 0.01). The number of estimated estrous cycles per live foal was 1.78 ± 0.12, including foal heat ovulation. Leptin was correlated with BCS (0.41; P < 0.001), but in the present study, plasma leptin concentrations on late gestation and early lactation did not influence fertility results. At 90 days of age, lower growth performances were obtained in foals which dams presented negative BCS changes on the first 3 months of lactation (P < 0.05). In conclusion, BC changes at early postpartum period influence the reproductive efficiency of broodmares and the growth of their suckling foals. These findings are important to help breeders on management options concerning feeding strategies in the Lusitano production systems and others under similar conditions.

Review: Feeding conserved forage to horses: recent advances and recommendations

The horse is a non-ruminant herbivore adapted to eating plant-fibre or forage-based diets. Some horses are stabled for most or the majority of the day with limited or no access to fresh pasture and are fed preserved forage typically as hay or haylage and sometimes silage. This raises questions with respect to the quality and suitability of these preserved forages (considering production, nutritional content, digestibility as well as hygiene) and required quantities. Especially for performance horses, forage is often replaced with energy dense feedstuffs which can result in a reduction in the proportion of the diet that is forage based. This may adversely affect the health, welfare, behaviour and even performance of the horse. In the past 20 years a large body of research work has contributed to a better and deeper understanding of equine forage needs and the physiological and behavioural consequences if these are not met. Recent nutrient requirement systems have incorporated some, but not all, of this new knowledge into their recommendations. This review paper amalgamates recommendations based on the latest understanding in forage feeding for horses, defining forage types and preservation methods, hygienic quality, feed intake behaviour, typical nutrient composition, digestion and digestibility as well as health and performance implications. Based on this, consensual applied recommendations for feeding preserved forages are provided.

Effects of foaling season on growth and development of Lusitano suckling foals raised on extensive grazing systems

Most Lusitano stud farms in Portugal are based in extensive grazing systems. In these systems, mares and foals are bred outdoors throughout the year, being pasture an important part of their diets. However, grass production is highly dependent on Mediterranean climatic conditions, with hot and dry summers. Therefore, a field study was conducted in order to evaluate the effects of foaling season on growth and development of the Lusitano suckling foal. One hundred and eight foals from four stud farms (A, n=39; B, n=33; C, n=12; D, n=24) were monitored from birth to six months of age, throughout three (A and B) and two (C and D) years. Monthly, foals were weighed (BW) and withers height (WH), girth (G) and cannon circumference (CC) were measured. According to birth date, two main foaling seasons were considered: February-March and April-May. A mixed linear model allowing for repeated measures on time was used to assess the effect of foaling season, stud farm, gender and their interactions on body weight, withers height, girth and cannon circumference. Quadratic effect of time was included in the model. The effect of foaling season was significant for withers height and girth (P<0.05) with higher values for foals born in February-March. Differences between stud farms were observed (P<0.001) for BW, WH, G and CC, which are probably linked with feeding options and pasture quality. The effect of gender was only significant on CC (P<0.05) with lower values registered in fillies. In the present study, foals born in February-March seem to have better development performances compared with foals born in April-May. Since pasture production and quality usually decreases from the end of May, these results suggest that April-May foaling mares may need a supplement to dry pasture, in order to support milk production and to promote an adequate foals’ growth and development.

Nutritional status of Lusitano broodmares on extensive feeding systems: body condition, live weight and metabolic indicators

The present research aimed to evaluate the effects of foaling season and feeding management in extensive systems on the nutritional status of Lusitano broodmares throughout the gestation/lactation cycle, by assessment of body condition (BC), body weight (BW), and some blood metabolic indicators. Four groups of Lusitano broodmares (A, B, C, D) were monitored during four years, in a total of 119 gestation/lactation cycles. All mares were kept on pasture, and A and B mares were daily supplemented. Monthly, mares were weighed and BC evaluated. Suckling foals from these mares were also monitored for BW and withers height. Glucose, non-esterified fatty acids, urea and albumin concentrations were determined in blood. BW changes were influenced by reproductive stage and foaling season (P<0.001), reflecting also pasture availability. Changes on BC were observed (P<0.05), although with small amplitudes within each group. Higher scores were reached at the end of spring, decreasing 0.25 point until late summer. Early foaling had also a marked effect, hindering the recovery of BC along the cycle. Glucose values decreased from late gestation to early lactation (P<0.05) and lower levels were recorded during the summer months. Uremia was mainly influenced by the reproductive stage (P<0.05). Under nutrition was not detected. Foals born in February-March had higher average daily gain than those born in April-May (P<0.05), probably reflecting differences in milk production of the mares. BC and BW changes and, particularly, blood indicators showed an overall balanced nutritional status, reflecting an adaptation to feed availability and climate.

The Effect of Coumestrol on Progesterone and Prostaglandin Production in the Mare: In Vitro and In Vivo Studies

ABSTRACT Coumestrol (Cou) is a plant-derived phytoestrogen that induces various pathologies in the female reproductive tract. Although effects of phytoestrogens on reproductive function in other species are well documented, their influence on progesterone (P4) and prostaglandin (PG) secretion in the mare is unknown. The aim of this study was to determine if Cou directly affects P4 and PG concentrations (in vivo) and endometrial PG secretion (in vitro) in the mare. In experiment 1, the mares (n = 4) were fed for 14 days on a diet containing increasing proportions of alfalfa pellets (250 g–1 kg/day). An additional 4 mares were fed a standard diet (control group). Sequential blood samples were obtained for 8 h after feeding on Days 13 and 14 (1 kg/day alfalfa pellets). Feeding the mares alfalfa pellets up-regulated PGE2 and 13,14-dihydro-15-ketoprostaglandin F2alpha (PGFM) and down-regulated P4 in the blood plasma compared to those in the control group (P < 0.05). In experiment 2, epithelial and stromal cells were exposed to E2 (10−9 M) or Cou (10−8 M) for 24 h. In the in vitro study, Cou increased PG secretion in epithelial and stromal cells (P < 0.05). In both types of endometrial cells, Cou up-regulated PTGS-2 protein expression (P < 0.05). Moreover, PGES and PGFS proteins were up-regulated by Cou in epithelial cells (P < 0.01). These results indicate that Cou can disturb reproductive function by affecting reproductive hormone secretion and altering the endometrial milieu through PG stimulation. Coumestrol therefore may impair physiologic regulation of the estrous cycle and early pregnancy.

Phytoestrogen coumestrol and its metabolite in mares’ plasma after clover mixed pasture and alfalfa pellets ingestion

Phytoestrogens are estrogens present in forages fed to horses. Phenolic rings in phytoestrogens enable their binding to cells estrogen receptors and may compete with 17-β-estradiol and influence the estrous cycle. The aim of the study was to determine whether phytoestrogens from clover mixed pasture and alfalfa are present in mare s plasma after their ingestion. In experiment I, Lusitano mares (n = 14) kept on mixed pastures with clover and grasses were bled monthly, from November to March. Pasture was collected, lyophilized and frozen. In Experiment II, stabled mares (n = 6) were fed with increasing amounts of alfalfa pellets (from 250 g to 1 kg/day), added to their regular feed, for 14 days. They were bled before alfalfa inclusion (control), and on days 13 and 14 at 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7 and 8 hours after feed intake. Coumestrol and its metabolite 4 -metoxycoumestrol concentrations were determined in plasma and feeds by HPLC. Data were analyzed by one-way ANOVA. Phytoestrogens were present in pasture and alfalfa samples, being 4 -metoxycoumestrol in the highest concentration. They decreased in pasture from November until March (P < 0.01). However, they were always identified in mares’ plasma, regardless of feeding system. In Experiment II, both active and conjugated forms of coumestrol and 4 -metoxycoumestrol in plasma were higher on days 13 and 14 than in control samples (P < 0.05). Coumestrol (free form) rose and reached a peak at 3.5 h after ingestion (P < 0.05), while its conjugated form peaked at 1.5 and 4 h (P < 0.001). The free form of its metabolite peaked at 1.5 h and the conjugated form at 0.5, 1.5 and 5 h (P < 0.001). These findings show that, in the mare, coumestrol and its metabolite increase in blood after estrogenic plants ingestion. Further studies should be carried out to evaluate their influence on reproduction in mares.